The maintenance of fruit tree orchards continually necessitates working at elevated positions around the periphery of each of the trees. Special vehicles have been adapted for this purpose, most of these featuring some sort of working platform at the end of a boom that can be swung in azimuth as well as elevated under the control of a workman standing on the platform. This type of vehicle has commonly been called a "cherry picker", although the principal orchard use has been in the trimming of the trees, rather than in the picking of the fruit. The latter is normally done manually through the use of ladders and moveable platforms, as the harvesting process would require an excessive number of the vehicles during the limited time in which the harvesting activity takes place. The name "cherry picker", has nevertheless stuck to this type of vehicle, and it is thus commonly identified in totally unrelated areas of use, where it is useful in performing service operations of various types at elevated positions. Maintenance of street lights, signs, and other overhead equipment will often involve the use of machines mechanically similar to those used in orchard maintenance.
In the operation of these vehicles, the primary lateral maneuverability is accomplished by the machines functioning as a ground vehicle, and steerable to a fairly close position to where the work has to be done. The lateral swinging movement of the boom therefore need only accommodate a fairly limited sector of freedom necessary for final placement of the worker in the lateral direction. The vertical movement necessary to perform this work must all be provided by the elevation of the boom, and thus the primary significance of the freedom of movement of the boom is in elevation, rather than azimuth. A relatively limited sector of freedom of lateral movement is all that is necessary, as this freedom is supplemented by the ground maneuverability of the vehicle. In the construction of these vehicles, cost is a major consideration, as well as the ability of the vehicle to handle relatively rough and soft terrain. These requirements place a considerable premium on the lateral stability of the vehicle for a given total weight. It is important that there be no tendency for the vehicle to tip over, even on sloping ground, when the pulpit containing the workman and his equipment are swung laterally to the limit position.